1. Field of the Invention
The present invention relates to a storage shelf that stores therein a front-opening unified pod (FOUP).
2. Description of the Related Art
A semiconductor conveyance system is provided with a storage shelf that temporarily stores therein FOUPs as wafer carriers. Examples of the storage shelf include one provided along a track of an overhead carrier and one suspended from a ceiling, such storage shelves may be subjected to vibration transmitted when the overhead carrier travels. Because wafers are products that require high precision, it is desired to reduce the effect of the vibration.
As a mechanism for preventing vibration, one described in Japanese Patent Application Laid-Open Publication No. 2012-15371, for example, is known. In the one described in Japanese Patent Application Laid-Open Publication No. 2012-15371, a receiving base on which a load is placed is provided with a viscoelastic body.
In general, to reduce vibration by using a vibration-isolating member (elastic body), the spring constant of the vibration-isolating member needs to be set lower so that the ratio of natural frequency of a system including an object to be vibration-isolated and the vibration-isolating member to the natural frequency of an input vibration becomes higher. However, when the spring constant of the vibration-isolating member is set lower, a problem may occur in that the object to be vibration-isolated cannot be supported while the elasticity of the vibration-isolating member is maintained.